A method for correlating natural aging data and its application toinsulation aging in nuclear power plants

摘要

A mathematical model has been developed to compare the aging ofpolymers in a nuclear reactor environment with that under acceleratedlaboratory conditions typical of those used in qualification. The agingstresses under consideration include temperature and gamma-radiationintensity. The proposed method is based on the hypothesis that severalmeasurable properties of a polymer are continuous functions of time,with time shifted in a fixed manner according to the imposed stresses. Amajor feature of the model is that other than smoothness, no attributesof the functions connecting properties with aging time have to beassumed. While available data from naturally aged specimens are spotty,preliminary results indicate that the method does work